We’ve widely acknowledged that the anti-Xa assay, currently employed to monitor heparin therapy, may be readily adapted to measuring direct oral anti-Xa antthrombotics, and at least three hemostasis diagnostics manufacturers have developed and validated rivaroxaban and apixaban calibrators and controls for this purpose. These await US FDA clearance. Meanwhile, we estimate oral anti-Xa antithrombotic efficacy with the prothrombin time. A colleague has asked, what does the lab offer when a surgeon chooses to transition a patient from rivaroxaban to heparin in preparation for major surgery, an everyday occurrence? Since the PT doesn’t measure heparin and the PTT doesn’t respond to rivaroxaban, it seems the simplest way to document rivaroxaban clearance before starting heparin is to employ the anti-Xa assay on a RUO basis. Do any of our participants have an alternative recommendation?
Jan 12 2016
Comments (6)Anticoagulant Therapy
Thinking of the transition,
Thinking of the transition, are not the anti-Xa tests for rivaroxaban influenced by heparin and vice-versa?
We use our antiXa kit (FDA
We use our anti-Xa kit (FDA-approved) to monitor five different anticoagulants, including rivaroxaban and apixaban using non-FDA approved calibrators and controls.
Wouldn’t PT, as a global
Wouldn’t PT, as a global assay influenced by multiple coag factors, as well as lupus anticoagulants (for some of the tests on the market), be a poor choice to rely on to figure out if rivaroxaban has completely left the system? I would think an anti-Xa assay, even with LMWH, UFH, or hybrid calibration would be much more sensitive to rivaroxaban on board compared to a PT.
From Donna Castellone, New
From Donna Castellone, New York Presbyterian Medical Center: We are just in the process of bringing this testing into our lab, RUO, request of physicians.
Dr. Favaloro states it like
Dr. Favaloro states it like it is in the US. The FDA is stifling attempts to measure the amounts of the anti-IIa and anti-Xa drugs with the exception of heparinoids. There is no logical reason for blocking these tests other than the FDA approved the DOACs under the illusion that at no time did these meds have to be measured. Of course that was the manufacturers’ claims they were taking for granted. We heard the same things when the LMWHs were approved back in the late 1980’s. Of course we know how that turned out. The FDA‘s attempt to take over the use of LDTs further shuts down laboratory innovation in getting assays that are desperately needed into the medical laboratory arena to assist the physician in using the DOACs properly with low risk to the patient.
Apologies to the US, but I
Apologies to the US, but I live in Australia, where the FDA doesn’t stifle diagnostic advances, and we have been offering anti-Xa testing for all the anti-Xa agents, including rivaroxaban and apixaban, for over a year now.